I've stored my car for the winter and unfortunately I can't leave it on a tender. My options are: run the car once every few weeks, or remove the battery completely and put it on a tender.

Could someone PLEASE give me a concrete answer as to the repercussions of removing the battery for an extended amount of time (5-months)? I've read a lot of scare stories about the computer going mental, but other than resetting the clock and windows, is there REALLY any concern about doing this?

If it helps, I have a eBay BMW Specific OBD cable, so can I make a "backup" or something??

I think if the battery is removed from the vehicle for an extended period of time, doesn't the vehicle go into what is referred to as "transport mode" which restricts the functions of several key accessories? This might require a trip to the dealer to get it out of this mode and operating normally.

I have an 08 si roadster. Last year I filled tank, put in Sta-Bil, parked in storage warehouse, disconnected the negative terminal form battery and came back four months later. Hooked cable back up, started right up. Reset radio presets, re-initialized windows and had a wonderful summer. Just did the same thing two hours ago and expect the same results. You'll get all sorts of advice but that's what worked fine for me. Oh, forgot, I put a cover over it.

Thanks for the input guys. I also got verification from a reputable mechanic that he just disconnects the negative terminal and lets the car sit. Apparently it won't lose any memory, and I don't mind resetting the clocks/windows. I'm going to try to remove the battery and keep it on a tender over the winter, seeing that the vehicle is going to be in an unheated space.

He was specific NOT to start the car until it is ready to come out of storage.

I remove the battery completely every winter on my '05 and have had zero problems so far. Place on a Ricklefs charger and you're good to go. I don't do the window reset as I've never had a problem with the default.

8 years ont the same battery... I guess I should start looking for a new one soon

Starting a car in storage is just about the worst thing you can do for it.

While I don't disagree, can you tell me the reason behind this? I initially figured that starting it and letting it warm up might be good to keep the oil in places it should be. PS: The advice came from Rocco @ RMP, so I trust it, along with what you're saying.

While I don't disagree, can you tell me the reason behind this? I initially figured that starting it and letting it warm up might be good to keep the oil in places it should be. PS: The advice came from Rocco @ RMP, so I trust it, along with what you're saying.

I think there was a thread here that said that these cars should be driven pretty well right after you start them. In your case, the car will sit idling while the engine warms up. That means though that the exhaust will get really hot and the transmission won't be loaded much. I'm sure others will chime in with better info on why that is not a good idea.

To avoid issues, if you really want to move the oil around, it may be an idea to put the battery back in at mid-winter, pull off the plug wires (noting where they go) and crank the engine 3 or 4 times. That should move the oil around. Then put the plug wires back, remove the battery again, and await spring.

I remove the battery completely every winter on my '05 and have had zero problems so far. Place on a Ricklefs charger and you're good to go. I don't do the window reset as I've never had a problem with the default.
soon

Ditto, I will store my car soon for the fourth winter and I've never had to do a window reset.

While I don't disagree, can you tell me the reason behind this? I initially figured that starting it and letting it warm up might be good to keep the oil in places it should be. PS: The advice came from Rocco @ RMP, so I trust it, along with what you're saying.

The problem is that it leads to condensation on the internals.
The oil never really gets up to full operating temperature to drive moisture out.

I've seen this doing oil sample testing. (in good weather)
If i don't do a full warm up (drive at least 20min) trace water will show in the sample.

To help clarify the power window initialization process and why, this is copied from my 08 manual. FWIW, It may be that only roadsters are affected. When the door is opened on the roadster, the window goes down about 1/2 inch to clear the lip on the cloth top. Likewise on closure, the window then goes up 1/2 inch to seal. Further, on top down button push, the windows go down halfway then on cycle completion return to full up unless a button is pressed to interrupt(stop) the process.

Power Window Initialization

After a power supply interruption, for instance after disconnecting the battery, the pinch protection system must be reinitialized.

Roadster: when the convertible top has been stored in the convertible top com-partment for an extended period of time, e.g. in the winter months because the hardtop was being used, it may also be necessary to reinitialize the pinch protection system.<
Ensure that the doors and the Roadster's convertible top are closed before initializing.
1. Open the window completely.
2. Press the switch 4 times within approx. 10 seconds.
Afterward, perform the following procedure twice for each window:
1. Close the window completely by pulling the switch.
2. After the window is closed, keep pulling the switch for approx. 2 seconds.
3. Open the window completely by pressing the switch.

Hi guys; a quick update. After 5 long months, I got the car out last week. Went in, re-installed the battery, it fired up right away. Other than needing to reset the power windows (PITA by the way), and setting the clock, so far everything else is OK. The radio seems to remember presets too.

So, from my experience, there is no "Transport Mode" issue with completely disconnecting the battery for extended periods.

As for the power windows, I tried at least a dozen times, got the passenger one working, but the driver's side was wonky---even completely unresponsive at times. Turned it off and let the car sit a few minutes, then tried with the car running, and finally got the driver's side. The procedure written above works, but seems finicky.

Hi guys; a quick update. After 5 long months, I got the car out last week. Went in, re-installed the battery, it fired up right away. Other than needing to reset the power windows (PITA by the way), and setting the clock, so far everything else is OK. The radio seems to remember presets too.

So, from my experience, there is no "Transport Mode" issue with completely disconnecting the battery for extended periods.

As for the power windows, I tried at least a dozen times, got the passenger one working, but the driver's side was wonky---even completely unresponsive at times. Turned it off and let the car sit a few minutes, then tried with the car running, and finally got the driver's side. The procedure written above works, but seems finicky.

Great to hear. Just a few days ago, I was talking to a guy that disconnected his battery (pretty sure his car is an older Toyota) for an extended period of time and his car pretty much lost its mind. Even the key fobs stopped working...

Yes, there was a a log of conjecture even here on the forums with "Transport Mode" and the car self destructing, etc. I had a lot of reservations to do it, and I even ended up calling an indie shop that has a lot of experience with these cars about it and he said it's fine.

I was on the edge of my seat when I plugged it all in, and other than perhaps needing an extra 1/2 second of ignition, she fired up without drama. Now if I could just get the smell of all the fabric softener sheets I stuck in all over the place out Need a good top-down blast, but its been under 50F here lately.

Once again, I hooked the neg terminal up after five months under cover and the car started up and ran smooth with no issues. It's great to be on the road again with the top down. Here's to another great summer!